1. Field of the Invention
Exemplary embodiments of the present invention relate to a cable retainer that serves as a coupling device between a connector and a fiber optic cable and a method for coupling a connector and fiber optic cable with a cable retainer. In particular, the exemplary embodiments relate to a cable retainer having a central grooved channel that creates a free floating ferrule design providing a more efficient assembly, greater optical alignment capability, and increased manufacturability.
2. Description of the Related Art
In the communication field, fiber optic cables have exemplified a viable technological advantage over the traditionally used copper wires. For example, when compared to the copper wires, fiber optic cables exhibit greater bandwidth, faster connection speeds, lower transmission loss (thus a longer transmission range), and no electro-magnetic interference or cross-talk. Thus, from a technological stand point, replacing copper wires with fiber optic cables would greatly improve the quality and performance of transmissions in the communication field.
From a commercial standpoint, however, fiber optic cables have not yet proven to be a complete alternative to copper wires. For example, to reach full commercial potential in the communication field, a product must be relatively easy to use on the go or in the field, and must be hardened to avoid degrading the signal quality. Contrastingly, the process of terminating a fiber optic cable with a connector in such a manner has traditionally been a tedious and complex job requiring special equipment and training, and has thus prevented the full commercial potential of fiber optic cables from being realized.
In an attempt to increase commercial potential, a series of fiber optic connector kits have been produced to ruggedize fiber optic cables for field applications. Generally, these kits pre-terminate the cable with a connector thus relieving the need to do so in the field.
A typical fiber optic cable contains an optical fiber, a buffer which surrounds the optical fiber, strength members, aramid yarns, and a cable jacket as shown in FIG. 1. When the fiber optic cable is terminated with a connector, the cable is prepared to expose the fiber, buffer tube, strengthening members and aramid yarns. A portion of the buffer tube is stripped back to expose the fiber, and the fiber end is then polished and fixed to the connector forming a connector subassembly. Once the connector subassembly is formed, the subassembly is inserted into a coupling device to further support the connection.
One example of a coupling device is illustrated as a crimp housing in U.S. Pat. No. 7,090,407. As shown in FIG. 3, the crimp housing is comprised of two half-shells that are pinned together to secure a connector subassembly. When attaching the coupling device to the connector subassembly, epoxy is inserted into strengthening member conduits of a first half shell. The optical subassembly is then placed into the first half shell whereby the strengthening members are inserted into the strengthening member conduits of the first half shell and the buffer tube is inserted into a separate central conduit. Epoxy is then injected into the strengthening member conduits of the second half shell. The second half shell is then placed on top of the first half shell and pinned, thereby capturing the connector, buffer tube, and strengthening members. As a last step, a crimp band is slid over the two half shells capturing the aramid yarns and the terminated cable end is cured for 45 minutes at 130° C.
Although the two half shell design has served as an initial design, such a design introduces assembly and alignment difficulties. For example, the fact that there are two half shells doubles the number of parts which inherently increases the manufacturing difficulties with respect to yield and cost. Furthermore, the need to pin the half shells together during assembly introduces the need for complimentary pin and hole locations between the half shells, thus reducing the tolerance for error when manufacturing the shells.
Additionally, when connecting the fiber optic cable and connector, it is important that the connector and cable are properly aligned to ensure that the connection does not degrade the quality of the communication. However, when inserting the fiber into the two half-shell design, the position of the subassembly is not secured until the two half shells are pinned together, thus allowing for the possibility of movement. Furthermore, once the shells are pinned together, the shells rigidly hold the fiber reducing the capability to adjust the optical alignment between the connector and cable.
A second example of a coupling device is illustrated in FIG. 2. The coupling device is formed with a central tunnel extending the length of the device and two arms extending from one end of the tunnel portion. With this design, a fiber optic cable is first fed through the tunnel and past the two arms. The fiber is then subsequently prepared for connection and, in turn, a connector is adhered to the fiber forming a subassembly, as described above. The subassembly is then pushed backwards into the tunnel until the connector passes the outer ledges of the arm. Once pushed back, the subassembly is essentially snapped into position with the ledges preventing the subassembly from moving forward out from the tunnel, and the tunneled portion blocking the cable from moving backwards into the tunnel.
This second example, however, also poses additional alignment and assembly issues. For example, the feed through tunnel requires the fiber optic cable to be first fed through the tunnel before attaching the connector, thereby introducing assembly difficulties. Additionally, the feed through tunnel rigidly attaches the cable making it hard to properly align the connector and cable.